QT2022/32 - Data Sheet: DS3051
Internal Limitations
The STS-1 overhead bytes are organized internally into groups of 8 bytes each. The STS-1 groups are [1..8],
[9..16], [17..24] - [185..192]. For a given overhead byte within an STS-1, only one byte may be overwritten within a
given group. For example, the A1 byte of STS-1 #1 and the A1 byte of STS-1 #2 cannot both be overwritten simul-
taneously. However, the A1 byte of STS-1 #1 and the A1 byte of STS-1 #9 can be overwritten simultaneously.
This rule does not affect bytes at different locations within the STS-1 (e.g. the A1 and K2 bytes of STS-1 #1 can be
overwritten simultaneously).
7.3.10 Programmable Overhead Byte Extraction
This feature allows the extraction of 3 bytes in the WIS RX SONET frame. The extraction is limited to the transport
overhead and path overhead bytes only. The location and number of frames is determined through 3 programma-
ble registers, located at MDIO registers 2.C611h - 2.C613h. Three separate control bits are used to initiate
extraction of each byte, located in register bits 2.C610h.2:0. After the bytes are extracted, their values are stored in
3 separate registers, using the lower 8 bits of MDIO registers 2.C614h - 2.C616h.
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